The present invention relates to an image reading method comprising the steps of reading an original image, signal-processing the read image and generating an output image, exposing a photosensitive material with an exposing signal, and using the output image as the exposing signal for the photosensitive material so as to prepare a printing plate.
The conventional image reading apparatus, has generally been a drum scanner which has an input drum, on which input drum an original to be read is affixed by pins or the like, and a scanner for reading the original as the drum rotates. In this conventional apparatus the read image is outputted onto photosensitive film material. In order to assure that the desired image will fit onto the film, the size of the film is calculated in order to estimate the position of the image on the output film, then the original is affixed to the input drum in a proper orientation to assure capture of the desired image. Consequently, there are problems such as loss of the output film and loss of efficiency due to the effort required for the operator's determining the optimum parameters of the scanning operation.
In addition to the conventional image reading apparatus of a drum scanner type, another conventional image reading apparatus is a flat bed type (plane scanning type) the flat bed reader gives little practically no consideration on how to read the desired image in an original with reference to the desired input size and the image output size of the original image. As a result, large loss is apt to be generated in the volume of the photosensitive material considered in outputting the entire original, as well as the scanning reading time of portions of an input original that are not desired.